1. Field of the Invention
The present invention relates to a signal transceiving circuit, and particularly relates to a signal transceiving circuit that can omit the noise caused by nearby transmitters. The present invention also relates to a noise reduction circuit that can be utilized to the signal transceiving circuit.
2. Description of the Prior Art
FIG. 1 is a prior art signal transceiving circuit. As shown in FIG. 1, the transmitter 101 outputs an output signal OS to a receiver 105 of another transceiving circuit via a cable 103, and the receiver 107 receives an input signal IS via the cable 103. However, in a current transceiving circuit, a group consisted of a transmitter 101 and a receiver 107 always shares the same transmitting lines, as shown in FIG. 1. In this situation, the transmitter 101 can be regarded as a nearby transmitter for the receiver 107. Such structure will cause the output signal OS to generate noise to the input signal IS, and the quality for the receiver 107 to receive the input signal IS is also affected.
Some inventions are developed to solve this problem. For example, the U.S. patent with U.S. Pat. No. 6,744,831 has disclosed such technology. As shown in FIG. 3 thereof, this patent utilizes a device 88 to counteract the noise caused by the output signal to the input signal. However, such kind of prior art needs extra circuits and accurate control to omit noise. By this way, a larger circuit area is needed, and design complexity, production cost also increase.